Starting Difficulty
 

Hi there. I am completely new to Model A's and need some help. We have just finished restoring a 30 Sport Coupe, including motor rebuild and new replacement Zenith Repro Carb. When it was first started, the motor started right up and idled very smoothly. Ran for about 20 minutes. Shut off and immediately restarted fine. A short while later, the car struggled starting. Would start to fire and struggle running over a few seconds. When finally got it started close to 10 minutes later, it ran super rough (not firing on all cylinders). With throttle applied, back fired numerous times through carb. After a few minutes it completely smoothed out and idled perfect again. I let it sit for two days and tried to restart. Pulled choke and it immediatly fired, but stumbled again like previous day. When finally got it running it ran super rough again, backfiring and appeared to drip some excess gas out of carb. 5 minues later it smoothed out completely like a flip of a switch. Acts like I am flooding out a cyliner or two. What am I missing that must be obvious? I just have zero experience but want to learn.

Re: Starting Difficulty
 

you HAVE re-torqued the head bolts now its had a hot cold cycle right?

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When starting, did you turn the GAV counterclockwise 1/2 to 1 turn and close it back to about 1/4 turn open when started? Try that first. It also sounds like there might be a sticky intake valve. Perhaps one of the engine guys can chime in and shed more light. You said you just finished restoring....so the car has probably been sitting some time without fresh fuel in the tank. Is it possible you might have debris/rust coming from the gas tank?

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Take the new carb apart and blow out all passages. Something may have been left from machining or something may have gotten in from the tank and lines.

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Moisture in the distributor? Are you in a high humidity area? as mentioned sticky valves, use mmo. Head gasket leaking water into the cylinder, or crack. ( usually water will end up in the oil with this problem).

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Great replies. I will review each one. I have re torqued head bolts. Put in new gas and filter looks clean. I did have seepage around head gasket but did not see anything in oil. Re torqued and put some premium stop leak in and seepage is gone. Thx for any ideas.

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I'm less than a year into having an A so far be it from me to suggest anything too substantial but from my own experience are you remembering to set the timing handle up each time you start it even when warm?

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No one has suggested checking the ignition points yet. They may have closed up and that could cause some of your symptoms. The standard gap is .020"

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I am starting with the timing full upward. The first time couple of times I started it it ran excellent and idled fine. AS month later and it would barely fire and was not getting any gas in the carb bowl. It was a no-name replacement carb so I put a new zenith on it. It started right up cold that time and idled great for 15 minutes. I shut it down and restarted it fine. The next few times it acted like 1-2 cylinders were loading up and ran very rough with popping in the carb and exhaust. It eventually goes away and idles fine and sounds great. Last time it did that cold and took 3-5 minutes, dripped some gas out of the carb and then the sound completely changed and ideled great. Seems like points would not get better, Could it be as simple as idle mixture is way off? It is a new cap and rotor. Car is in cool basement/garage in upstate ny.

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"new Zenith" Are we talking a fork lift carb or a new zenith?? Where did you get the carb?? Have you tried adj it?? Do you have good fuel flow at the carb??
Paul in CT

Re: Starting Difficulty
 

you have alot going on since the car is a new rebuild with many changed parts...
i would hook up a spark tester to make sure your not having an issue on the electrical side.... i look for a steady intensity and rythmetic flash. if the spark flutters or dims when the problem occurs you need to refocus on this area

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Could you be running the engine for too short a time and loading the plugs? I don't like to start any gas engine unless it's run long enough to fully warm the oil and burn off moisture. This would be 30 minutes or longer for car engines in the summer.

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sounds like its loading up with fuel after shutdown

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I purchased the carb from a local A parts distributor. New repro. I will look into spark. I want to get some help tomorrow so I can go out and short each plug while it is running rough to see if I can easily see what is not firing. Will need to inquire on spark tester. Just seems like it is fuel related, because it has run fine both stone cold and hot at differing times. Should I be shutting fuel off when shutting down? Hate to ask these basic questions but I am finding my way through the dark on this car. Trying to get it on road for my 90 year old father to enjoy.

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alot of driveabilty issues can act like fuel but its spark and visa versa... you need to diagnose which area is at fault first. i had a carb running to rich and by removing the vacuum line for the wiper off the manifold that let more air in to compensate for the rich mixture and it ran great...

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Open up the distributor and pull the lower plate. Check to make sure the flexible wire under the lower plate is in good condition. One of my club members had issues similar to what you are experiencing and replacing the wire cured it. While you are there make sure the point gap is set correctly.

Re: Starting Difficulty
 

exactly
a spark tester will point this out
a bad plate wire will cause the spark to flutter and be intermittent

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I shut the fuel off about 30 seconds before I turn off the ignition. My valve doesn't leak, so if I would forget to shut off the fuel it still wouldn't matter. If a hot restart is the problem, then the fuel could be boiling in the carb, so turning the gas off a minute or two before the ignition might be worth a try.

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I'll try shutting the fuel off and see if that helps the cold start. Should be pretty quick to verify. Also sounds liek checking spark as a starting point is well worth it. I don't have a tester but they look pretty basic at local parts store. Any suggestions on brand or type? Next I' try point gap and review the cable. I assume the spark tester would cover a cable issue too but I'll look.

Re: Starting Difficulty
 

Harbor freight has them but they are hard to see and crappy..
I like the ones I get from the snap on truck
but it looks the same as this one
http://www.amazon.com/Lisle-20610-In.../dp/B0002STSC6
i would go with this
put it between the cap and coil wire first

Re: Starting Difficulty
 

Perfect. That is identical to what they show locally. This is just so strange. It has run both great cold and hot as well as crappy at both extremes. If the cylinders are loaded up, won't I see a spark issue as well on the tester? I also am not sure if I am losing the same cylinder(s) each time and need to verify. I thought I would just short each to gound to see if it is a specific one.

Thank you very much for all your comments also. The anticipation of getting this on the road is killing me. As I stated, it is a present for my father. We had exact model/year color back in the 70s so we both can't wait.

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Wanted to post a photo of what I have

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The spark tester is available at Advance Auto parts.

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This is sounding more like an ignition primary circuit problem, such as a repro switch contact touching the gas tank, or the distributor lower plate wire touching ground.

If you have an original popout switch, the wire inside the cable could be old with worn insulation and the wire grounding out inside the cable.

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Need to ask, can this in anyway be a head gasket problem? My motor was rebuilt locally this past winter. I was getting seepage around the head bolts. That is now gone by retorqing and some head gasket sealant. New problem is the motor, once running seems to run hot. After less than 1/2 mile, water shoots from the overflow. I cleaned the radiator out by unhooking and soaking with drano for 15 minutes and then flushing. Flushed quite a bit of rust and I assume sealant out. Flushed the block with a hose and got some loose material out of that too. Now water appears clean each time flushed. When I shoot the head with IR thermometer I am seeing about 180-190 after idling for quite a while and 200-210 after short drive and radiator is pretty consistent across all tubes at about 186. I shot the spark plugs and see about 225 on the base of them. I see very little difference and all are within 5-10 degrees, top to bottom. It is an old radiator and possibly it is not tranfering heat well. I also am currently trying this without the hood on, so I don't know if that could have impact on cooling. Before I assume the radiator is the culprit, I want to make sure my rough running at startup is not connected to this via a head gasket issue. I just don't know enough to diagnose this.

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Do a compression test...and post results. If you can start engine, run it at idle until warmed up, than repeat compression test and post results. Also, Check your oil to make sure you have no water/coolant mixed in. Another thing to look at is make sure you have a good seal between manifolds and block. If it is starting hard, you could spray starting fluid around manifold gasket while cranking to see if that helps starting. If so, you likely have a bad seal between manifolds/block.

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ike the clear distributor caps to help isolate problems also. I think Mikes still sells them?

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I will do a compression test this week. It is the strangest thing. It runs horribly rough and then after 3-5 minutes of this, instantly the sound of the engine changes, it smoothes out and runs great. Considering the temperature issue, was wondering if they could be connected before I spend the money on a radiator. Thx!

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You shouldn't have any crap coming out of the block on a freshly rebuilt motor as long as it was cleaned and tanked properly. A new or rebuilt radiator goes hand in hand with a new engine. To many overlook this fact and I feel the rebuilders don't stress it enough. It sounds like your feeding junk from a clogged radiator back through the block.

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This was posted earlier today - Very successful radiator and block cleanout.

http://www.fordbarn.com/forum/showthread.php?t=177658

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My complete ignorance on the new rebuild and old radiator. Seems so obvious now.

I am leaning toward the head gasket or intake gasket being an issue, just due to the dramatic change in engine sound when it starts to run well. The exhaust tone even seems to change. Even after turning off for about 30 minutes, the cycle starts all over until time/temp rises and then it smoothes out again. May have nothing to do with my temperature issue and may still end up with a radiator when it is all said and done. The water flow appears to be good through it with the consistent temps, row to row. I just am stumbling my way through everything it appears. If anyone knows of a good shop/home shop in upstate NY/northern PA, I would love to take it for professional help. Days are getting short here and with Hershey around the corner, winter will be here soon.

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Do you have a fuse in the system? I have seen them get loose at the rivets and not make good contact. Bypass this system and see if it runs better.

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yes to the fuse and it appears to not be an issue. I had jumpered across it just to be sure. Ignition/spark appear to be good. I appear to have a good spark at each cylinder. I did swap a new coil in for the ease of it with no difference. Thought it could be reacting to temperature change. I am going to do compression but need to get adapter for the larger plugs. May call a couple older repair shops to see if by any chance they have something but may be faster to just order adapter in the morning.

I did see a post about cooling difference in radiator. I am only seeing about 5 degrees top to bottom so I may not have sufficient cooling aside from my other issue or who knows, they may be connected.

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Sounds like your cap and rotor is junk. Try swapping it out with a good used one

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Your radiator needs help if you only see 5* cooling from top to bottom. Get it fixed before the engine gets ruined. You should see at least 20 to 30 degrees cooling from top to bottom.

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Glad to see this thread, my friend has had the same problem. Will send him here, saving thread on favorites. Thanks

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My car runs rough when I don't start it for a few weeks so I need to let it run for a long time to clear it up. my problem is I live in a sauna (Okinawa Japan) but now that I know what the cause is I keep a can of contact cleaner around to clean moisture out of the cap before I start it. your carb drib sounds like a float adjustment problem.

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Bad news. I just checked compression on this newly rebuilt motor (about 1-2 hrs total run time). I get 60-62 on cylinders 1, 2 and 4. ), Zero, Zip on cylinder 3. These were all at cold condition. Again, it runs real rough (go figure) and then after a few minutes runs fine. Is this a head gasket issue or a valve issue?

Re: Starting Difficulty
 

do a leak down test before you tear into anything
call the builder also

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Is a leak test the same as Vacuum Gauge Test hooked into the intake?